Hydrolysis constant for a salt of weak acid and weak base would be

• A

  ${\mathrm{K}}_{\mathrm{h}} = \frac{{\mathrm{K}}_{\mathrm{w}}}{{\mathrm{K}}_{\mathrm{a}}}$

• B

  ${\mathrm{K}}_{\mathrm{h}} = \frac{{\mathrm{K}}_{\mathrm{w}}}{{\mathrm{K}}_{\mathrm{b}}}$

• C

  ${\mathrm{K}}_{\mathrm{h}} = \frac{{\mathrm{K}}_{\mathrm{w}}}{{\mathrm{K}}_{\mathrm{a}} {\mathrm{K}}_{\mathrm{b}}}$

• D

  ${\mathrm{K}}_{\mathrm{h}}=\frac{{\mathrm{K}}_{\mathrm{w}}{\mathrm{K}}_{\mathrm{a}}}{{\mathrm{K}}_{\mathrm{b}}}$